Preheat oven (electric cooker: 200°C/circulating air: 175°C/gas: level 3). Peel onions, dice roughly. Clean or peel the zucchini, carrots and potatoes, wash and chop coarsely. Wash rosemary and shake dry.
Mix all prepared ingredients with 1 heaped teaspoon of sea salt, some pepper and 4 tablespoons of oil on a fat pan (deep baking tray). Put the unpeeled cloves of garlic in a corner of the fat pan.
Roast everything in a hot oven for 45-60 minutes and turn the vegetable mixture once in between.
In the meantime, dice the soft tomatoes. Bring 1 l water, tomatoes, stock and tomato juice to the boil in a large pot. Cut the ciabatta into 8 slices and place them on a baking tray lined with baking paper. Sprinkle with 4 tablespoons of oil and sprinkle with some sea salt.
Take the fat pan with the vegetables out of the oven. Slide the baking tray with the ciabatta into it and roast at the same temperature for 8-10 minutes until crispy brown.
Set aside the garlic for the crostini and rosemary. Add the rest of the vegetables to the tomatoes in the pot and bring to the boil once. Puree the soup. Season to taste with salt and pepper and sprinkle with rosemary needles.